1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a method for cutting a liquid crystal display panel to separate a plurality of unit LCD panels from the mother substrate.
2. Discussion of the Related Art
In general, a liquid crystal display (hereinafter, referred to as xe2x80x9cLCDxe2x80x9d) device displays a picture by individually supplying a data signal according to picture information to the liquid crystal cell arranged in a matrix form and controlling light transmittance of the liquid crystal cells.
In the LCD device, thin film transistor (hereinafter, referred to as xe2x80x9cTFTxe2x80x9d) array substrates are formed on a large mother substrate, and color filter substrates are formed on another mother substrate. By attaching the two mother substrates, a plurality of unit LCD panels are simultaneously formed. Since yield can be increased by simultaneously forming a plurality of the unit LCD panels on a glass substrate of a large area, a process of cutting the attached two mother substrates into unit LCD panels is required.
Conventionally, the cutting process includes a scribing process of forming a predetermined cutting line on the surface of the substrate with a diamond pen having a hardness higher than the glass substrate and a breaking process of cutting by applying a physical force. The cutting process of the unit LCD panel will be described in detail with reference to the accompanied drawings.
FIG. 1 is a schematic plane view showing a unit LCD panel formed from a TFT array substrate and a color filter substrate attached to face into each other.
In FIG. 1, an LCD panel 10 includes a picture display unit 13 having a plurality of liquid crystal cells arranged in a matrix form, a gate pad unit 14 connected to a plurality of gate lines of the picture display unit 13, and a data pad unit 15 connected to a plurality of data lines of the picture display unit 13.
The gate pad unit 14 and the data pad unit 15 are formed at the marginal portion of the TFT array substrate 1. The marginal portion does not overlap the color filter substrate 2.
The gate pad unit 14 provides a scan signal supplied from the gate driver integrated circuit to the gate lines of the picture display unit 13. The data pad unit 15 supplies picture information supplied from the data driver integrated circuit to the data lines of the picture display unit 13.
The data lines receiving the picture information and the gate lines receiving the scan signal are disposed to be perpendicularly crossed with each other on the TFT array substrate 1 of the picture display unit 13. At the crossed portion, a TFT is formed for switching the liquid crystal cells, and a pixel electrode is formed to be connected to the TFT for driving the liquid crystal cells. Further, a protective layer is formed at the entire surface to protect the electrode and the TFT.
At the color filter substrate 2 of the picture display unit 13, a plurality of color filters are formed to be separated by cell regions with a black matrix, and a common transparent electrode corresponding to the pixel electrode are formed at the TFT array substrate 1.
A cell gap is formed between the TFT array substrate 1 and the color filter substrate 2 so that the two substrates are spaced apart from and face into each other. The TFT array substrate 1 and the color filter substrate 2 are attached by a sealant (not shown) formed at the exterior of the picture display unit 13. A liquid crystal layer (not shown) is formed at the space between the TFT array substrate 1 and the color filter substrate 2.
FIG. 2 is a cross-sectional view showing a plurality of the unit LCD panels formed in the first mother substrate having the TFT array substrates and the second mother substrate having the color filter substrates of FIG. 1.
As shown in FIG. 2, a plurality of the unit LCD panels are formed in such a manner that one side of the TFT array substrates 1 is protruded as much as a dummy region 31.
This is because the gate pad unit 14 and the data pad unit 15 are formed at the marginal portion where the TFT array substrates 1 and the color filter substrates 2 do not overlap.
Thus, the color filter substrates 2 formed on the second mother substrate 30 are formed to be isolated as much as the dummy regions 31 corresponding to the area that the TFT array substrates 1 formed in the first mother substrate 20 are protruded.
Each unit LCD panel is disposed at the first and second mother substrates 20 and 30 so that the first and second mother substrates 20 and 30 are used at the maximum. Depending on a model, the unit LCD panels are generally formed to be isolated as much as the dummy regions 32. Dummy regions 21 for a process margin are also formed in the marginal portions of the first and second mother substrates 20 and 30.
After the first mother substrate 20 where the TFT array substrates 1 are formed and the second mother substrate 30 where the color filter substrates 2 are formed are attached to each other, the LCD panels are individually cut through the scribing process and the breaking process. The dummy regions 31 formed at the region where the color filter substrates 2 of the second mother substrate 30 are isolated. The dummy regions 32 isolating the unit LCD panels and the dummy regions 21 formed at the marginal potion of the first and second mother substrates 20 and 30, are simultaneously removed.
As shown in FIG. 2, in case of a model in which the dummy regions 31, 32, and 21 are formed on the first and second mother substrates 20 and 30, as the number of unit LCD panels which can be formed on the first and second mother substrates 20 and 30 is limited, efficiency in using the first and second mother substrates 20 and 30 is reduced and accordingly, productivity is decreased.
Taking the above problems into consideration, a cross-sectional structure of the first and second mother substrates in which the dummy regions 32 are not formed by preventing the unit LCD panels from being separated from each other, was suggested as shown in FIG. 3.
The cutting process to the unit LCD panels shown in FIG. 3 will now be described with reference to the sequential exemplary views, FIGS. 4A to 4J.
As shown in FIG. 4A, the first and second mother substrates 20 and 30 attached to face into each other are loaded on a first table 33.
Next, as shown in FIG. 4B, the first table 33 is moved in one direction to sequentially form a plurality of first scribing lines 42 on the first mother substrate 20 with a cutting wheel 41.
After the first and second mother substrates 20 and 30 in FIG. 4C are rotated by 90xc2x0, the first table 33 is moved back to its original position to sequentially form a plurality of second scribing lines 43 on the surface of the first mother substrate 20 through the cutting wheel 41.
FIG. 4D illustrates the first and second mother substrates 20 and 30, which are overturned and loaded on a second table 34. While the second table 34 is moved in one direction, the second mother substrate 30 is pressed by a breaking bar 44 along the second scribing lines 43 so that a crack is transmitted on the first mother substrate 20.
Next, as shown in FIG. 4E, the first and second mother substrates 20 and 30 are rotated by 90xc2x0. While the second table 34 is moved back to its original position, the second mother substrate 30 is pressed by the breaking bar 44 along the first scribing lines 42, so that a crack is transmitted on the first mother substrate 20.
As shown in FIG. 4F, the first and second substrates 20 and 30 are loaded on a third table 35. A plurality of third scribing lines 46 are sequentially formed on the surface of the second mother substrate 30 with a cutting wheel 45 by moving the third table 35 in one direction.
Thereafter, the first and second mother substrates 20 and 30 are rotated by 90xc2x0, as shown in FIG. 4G. A plurality of fourth scribing lines 47 are sequentially formed on the surface of the second mother substrate 30 with the cutting wheel 45 by moving the third table 35 back to its original position.
As shown in FIG. 4H, the first and second mother substrates 20 and 30 are overturned and loaded on a fourth table 36. The first mother substrate 20 is pressed by a breaking bar 48 along the fourth scribing line 47 by moving the fourth table 36 in one direction, so that a crack is transmitted on the second mother substrate 30.
Next, the first and second mother substrates 20 and 30 are rotated by 90xc2x0, as shown in FIG. 4I. The first mother substrate 20 is pressed by the breaking bar 48 along the third scribing line 46 by moving the fourth table 36 back to its original position, so that a crack is transmitted on the second mother substrate 30.
As shown in FIG. 4J, as the crack is transmitted on the first and second mother substrates 20 and 30 along the first through fourth scribing lines 42, 43, 46, and 47, the unit LCD panels are selectively unloaded by using a vacuum gripper 49 and conveyed to the equipment for the following process.
As mentioned above, in the conventional cutting processes for the unit LCD panel, a scribing process is performed four times and a breaking process is required four times while performing four rotation processes and two overturning processes.
Thus, two scribing units including a rotating unit and two breaking units including a rotating unit and an overturning unit are required. This equipment would occupy much space in the fabrication line. Thus, an installation expense and a space of the equipment are increased.
In addition, much more time is required for the scribing and breaking processes, resulting in a low productivity.
Accordingly, the present invention is directed to a method for cutting a liquid crystal display panel that substantially obviates one or more of problems due to limitations and disadvantages of the related art.
Another object of the present invention is to provide a method for cutting a liquid crystal display panel that reduces the number of scribing and breaking equipment and also reduces the time necessary for the overall process by minimizing rotations and overturnings in performing the scribing and breaking processes.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for cutting a liquid crystal display panel includes forming a first scribing line on surfaces of first and second mother substrates using first and second wheels, cutting the first and second mother substrates along the first scribing line, forming a second scribing line on the second mother substrate using the second wheel, and removing a dummy region from the second mother substrate by cutting the second mother substrate along the second scribing line.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.